Comparing different varieties

The genetically modified Bt maize being tested in this trial series contains several introduced genes, called ‘stacked genes’. Two different Bt genes make it resistant to its main chewing pests, the European corn borer and the Western corn rootworm . The corn borer caterpillars chew through the maize stems, while the larvae of the Western corn rootworm attack the roots of the maize plants. The two previous series of research projects tested Bt maize that was resistant to just one of the two pests. The maize being tested now also contains a herbicide‑resistance gene.

Trial design

At the start of the biological safety research into Bt maize, Bt maize was compared only with the isogenic variety, i.e. the conventional parent variety. In this trial series, two more conventional varieties are being grown in addition to the isogenic variety. It is suspected that differences in the incidence and abundance of individual insect species may be greater between different conventional varieties than between Bt maize and the isogenic variety.

There are also plans for plots on which the isogenic variety will be treated with a soil insecticide. In previous experiments it was found that an insecticide treatment had much more serious impacts on the living organisms in the field than the genetic modification.

Each of the maize variants is being grown on eight plots. They are distributed according to a ‘randomised plot design’. This means that the different varieties are distributed at random, but respecting certain conditions: plots of the same variety must not be placed immediately adjacent to one another, and there must be a similar number of plots of each variety around the edge of the field and in the middle.

Under the microscope: ground beetles, bees and butterflies

As in previous years, the researchers are focusing primarily on the small living organisms in the maize field. RWTH Aachen University is investigating possible impacts of Bt maize on the broad spectrum of insects and spiders found in the field. One of the things they will be researching is to what extent butterflies living at the edge of the field come into contact with Bt maize pollen.

A project being conducted by the Bavarian State Research Center for Agriculture is focusing specifically on ground beetles and spiders.

This series of research projects will also be looking at bees for the first time. The University of Bayreuth is investigating whether bees tolerate Bt maize pollen less well than conventional pollen.